1. Field of the Invention
The present invention relates to a radio access network system which includes a base station and a control apparatus (a radio network controller) and transfers IP packets including control data and user data in a network, a radio access method and a control apparatus.
2. Description of the Related Art
A method of transferring IP packets including control data and user data in the network has recently been defined in “Release 5 RAN IP Transport”. The “Release 5 RAN IP Transport” is a standard specification of “3GPP Radio Access Network” in a 3rd Generation Partnership Project (3GPP) as a standardization body of next-generation mobile communication. According to the definition, a control apparatus and a base station (Node B) is configured to set “Diffserve Code Points (DCP)” in IP packets.
Specifically, as shown in FIG. 1A, the conventional method specifies a priority of an IP packet by using 3 bits of “Precedence” in an 8-bit “ToS (Type of Service) field” in a second octet of the IP packet as QoS (Quality of Service) information. And the conventional method processes the IP packets in accordance with the QoS information as specified by the following four flags set in the “Precedence”.
(flag-1) packet delay characteristics: delay is kept to a minimum
(flag-2) throughput: throughput is maximized
(flag-3) reliability: reliability is maximized
(flag-4) cost: cost is kept to a minimum
As shown in FIG. 1B, the conventional method using the Diffserve technique defines a 6-bit DS (Differentiated Service) field in the ToS field, and specifies the process of the IP packets in a predetermined network domain, by writing a DSP which is a local value in a DS domain in the DS field.
However, the conventional method has not defined a method of notifying a determined packet format including setting the ToS field in the IP packets to the control apparatus or the base station, and a transmitting process over the radio line.
Also the standard specification of the 3GPP has not defined a method of determining the DCP in the respective network domains, a method of notifying the determined IP packet format to the control apparatus or the base station, and a method of using the DCP in the transmitting process over the radio line, etc.
Therefore, there is a problem in that priority transmission control of the IP packets cannot be carried out in an IP-based network, for example, the IP packets requiring real-time communication strict on delay cannot be transmitted with priority, so that it has been impossible to satisfy traffic requirements.